Registration Dossier

Administrative data

Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
2005-03-16 to 2005-09-27
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP guideline study. K2 score due to read-across.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2005
Report Date:
2005

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Deviations:
no
Remarks:
Minor deviations not influencing the outcome of the study.
GLP compliance:
yes (incl. certificate)
Type of study:
mouse local lymph node assay (LLNA)

Test material

Reference
Name:
Unnamed
Type:
Constituent

In vivo test system

Test animals

Species:
mouse
Strain:
CBA
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River deutschland, Sulzfeld, Germany
- Weight at study initiation: 18.5 - 21.9 g
- Housing: Individually in macrolon cages type III
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 7 days

ENVIRONMENTAL CONDITIONS
According to guideline

IN-LIFE DATES: From: 2005-07-27 To: 2005-08-08

Study design: in vivo (LLNA)

Vehicle:
dimethylformamide
Concentration:
6.25 %, 12.5 % and 25 % L-valine
No. of animals per dose:
5
Details on study design:
RANGE FINDING TESTS:
Not performed

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: Animal allocation by computer.
- Criteria used to consider a positive response:
3H-thymidine incorporation was compared between the different treatment groups. In evaluating changes in 3H-thymidine incorporation possible outliers were identified by means of the dose-response curve, as well as biologically relevant ranges (i.e. data within the range of background levels). Changes in 3H-thymidine incorporation in the test substance treatment groups were evaluated and expressed as stimulation index (SI). The SI was obtained by dividing the individual values of the 3H-thymidine incorporation, expressed as DPM (corrected for background), with the mean proliferation of the vehicle control group. Since also the DPM-data of the vehicle treated group are divided with its own mean DPM-data, this results in an average SI for vehicle-treated controls of 1. The decision process with regard to a positive response includes a stimulation index J3 together with consideration of dose response and statistical analyses.

TREATMENT PREPARATION AND ADMINISTRATION:
Once daily, during three consecutive days, the dosing formulations were applied on the dorsum of both ears (by means of pipetting 25 µl on each ear) of the test substances, the vehicles and the positive control.
On day 5 all animals received an intravenous injection with 250 µl of phosphate-buffered saline (PBS) containing 20 µl of 3H-thymidine in the tail vein.
Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)
Statistics:
Statistical evaluation was performed using SAS Online Doc ®, version 8.2, 1999, SAS Institute Inc., USA. Statistical evaluation of the data (body weights and 3H-thymidine incorporation) was performed by analysis of (co)-variance followed by an appropriate test like Dunnett’s multiple comparison tests. 3H-thymidine incorporation of treatment groups were compared to vehicle-treated animals. The validity of the model was tested by comparing the positive control and the vehicle-treated group. Probability values of p<0.05 were considered significant.

Results and discussion

Positive control results:
No effects on body weights or clinical signs were found after treatment with HCA. As expected, administration of HCA, which is a known sensitizer, resulted in a clear and statistically significant enhanced 3H-thymidine incorporation in the LLN (p<0.05). The calculated stimulation index of 16.7 supports this observation and demonstrates the
sensitivity/validity of the model.

In vivo (LLNA)

Resultsopen allclose all
Parameter:
SI
Remarks on result:
other: 6.25 % dose: mean SI = 1.8 12.5 % dose: mean SI = 1.7 25 % dose: mean SI = 1.9
Parameter:
other: disintegrations per minute (DPM)
Remarks on result:
other: see Remark
Remarks:
No significant differences in 3H-thymidine incorporation were observed between the L-valine treated groups and the vehicle treated group. Stimulation indices (3H-thymidine incorporation (dpm) divided by the average 3H-thymidine incorporation of the vehicle group) ranged from 1.7-1.9. 6.25 % dose: mean DPM = 3115.5 12.5 % dose: mean DPM = 2922.8 25 % dose: mean DPM = 3240.3

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Remarks:
Migrated information
Conclusions:
In a GLP guideline study according to OECD 429 L-valine was not able to act as a skin sensitizer when applied at the used dose levels The maximum dose was 25 % L-valine.